A systematic review and meta-analysis of obesity and COVID-19 outcomes

Abstract

Some studies report that obesity is associated with more severe symptoms following SARS-CoV-2 infection and worse COVID-19 outcomes, however many other studies have not reproduced these findings. Therefore, it is uncertain whether obesity is in fact associated with worse COVID-19 outcomes compared to non-obese individuals. We conducted a systematic search of PubMed (including MEDLINE) and Google Scholar on May 18, 2020 to identify published studies on COVID-19 outcomes in non-obese and obese patients, covering studies published during the first 6 months of the pandemic. Meta-analyses with random effects modeling was used to determine unadjusted odds ratios (OR) and 95% confidence intervals (CI) for various COVID-19 outcomes in obese versus non-obese patients. By quantitative analyses of 22 studies from 7 countries in North America, Europe, and Asia, we found that obesity is associated with an increased likelihood of presenting with more severe COVID-19 symptoms (OR 3.03, 95% CI 1.45-6.28, P = 0.003; 4 studies, n = 974), developing acute respiratory distress syndrome (ARDS; OR 2.89, 95% CI 1.14-7.34, P = 0.025; 2 studies, n = 96), requiring hospitalization (OR 1.68, 95% CI 1.14-1.59, P < 0.001; 4 studies, n = 6611), being admitted to an intensive care unit (ICU; OR 1.35, 95% CI 1.15-1.65, P = 0.001; 9 studies, n = 5298), and undergoing invasive mechanical ventilation (IMV; OR 1.76, 95% CI 1.29-2.40, P < 0.001; 7 studies, n = 1558) compared to non-obese patients. However, obese patients had similar likelihoods of death from COVID-19 as non-obese patients (OR 0.96, 95% CI 0.74-1.25, P = 0.750; 9 studies, n = 20,597). Collectively, these data from the first 6 months of the pandemic suggested that obesity is associated with a more severe COVID-19 disease course but may not be associated with increased mortality.

Figure 1

Systematic search strategy and COVID-19 outcomes reported in association with obesity. (A) PRISMA Flow Diagram showing the numbers of articles per stage of review, resulting in n = 22 full text articles reporting COVID-19 outcomes stratified on obesity status. (B) Six outcomes were reported by the 22 studies included in meta-analysis. The numbers of contributing articles per outcome are in parentheses. Numbers do not add to 22 because some studies report more than one outcome. (C) World map showing the locations where the included studies were conducted. The image was generated in BioRender with permission to publish.

Figure 2

Obesity is associated with more severe COVID-19 and an increased likelihood of acute respiratory distress syndrome (ARDS) and hospitalization. Random effects meta-analyses of odds ratios (OR) and 95% confidence intervals (CI) in obese versus non-obese patients for (A) presenting with severe COVID-19 disease (4 studies, n = 915 patients), (B) developing acute respiratory distress syndrome (ARDS) (2 studies, n = 96 patients), and (C) being hospitalized (4 studies, n = 6,252 patients). Non-obese is defined as the reference group.

Figure 3

Obesity is associated with an increased likelihood of requiring invasive mechanical ventilation (IMV) and admission to the intensive care unit (ICU) in the setting of COVID-19. Random effects meta-analyses of odds ratios (OR) and 95% confidence intervals (CI) in obese versus non-obese patients for (A) requiring IMV (7 studies, n = 1,261) and (B) admission to an ICU (9 studies, n = 3227). Non-obese is defined as the reference group.

Figure 4

Obesity is not associated with increased COVID-19-associated mortality. Random effects meta-analysis of odds ratios (OR) and 95% confidence intervals (CI) for the likelihood of death in obese vs non-obese COVID-19 patients (A) overall (9 studies, n = 20,597 patients and in studies from (B) North America (2 studies, n = 1,076), (C) Asia (3 studies, n = 586), and (D) Europe (4 studies, n = 18,935). Non-obese is defined as the reference group.